And more specifically, Levamisole is becoming something of a hot topic as a dangerous, but desirable for its ability to pass most purity tests. http://www.time.com/time/health/article/0,8599,1955112,00.ht... is one overview. The DEA journal Microgram has covered it a few times as well.
https://en.wikipedia.org/wiki/Cutting_agent
And more specifically, Levamisole is becoming something of a hot topic as a dangerous, but desirable for its ability to pass most purity tests. http://www.time.com/time/health/article/0,8599,1955112,00.ht... is one overview. The DEA journal Microgram has covered it a few times as well.